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Isotopiary

Published 4 September 2004

From Steuart Campbell

Your description of what goes on in a fast breeder reactor is incorrect (7 August, p 26). Fissionable plutonium is not produced by reactions between plutonium, uranium-238 and other uranium isotopes. It is produced by irradiating uranium-238 with some of the fast neutrons released by uranium-235 and plutonium-239 as they undergo fission. This converts uranium-238, via a series of intermediates, into plutonium-239.